Opportunities and Challenges of Municipal Planning in Shaping Vertical Neighbourhoods in Greater London

Production of housing in London is driven by three factors: a housing crisis that requires the construction of more than 1.6 million homes by 2025, a model of social housing production mainly delivered through private developers’ contri‐ butions, and a metropolitan governance structure through which housing targets are allocated to municipalities with highly unequal pressures, being inner London boroughs the ones with the highest targets to meet. In the context of a non‐prescriptive and liberalised planning system, this threefold scenario has resulted in the construction of unprecedented residential landscapes, dominated by high‐density and high‐rise buildings. Tower Hamlets Council is at the forefront of this challenge both in the UK and Europe and is trying to develop planning tools to shape them. This article discusses three innovative supplementary planning documents (SPDs) produced by the policy team that have had unequal success in shap‐ ing different aspects of this form of development: the South Quay Masterplan SPD, the High Density Living SPD, and the soon‐to‐be‐adopted Tall Building SPD. A comparative analysis of these planning documents and the perception of urban planners working at different stages of the planning process on the effectiveness and limitations of these SPDs in shaping vertical neighbourhoods shed light on the key factors influencing the role municipal planning can have in delivering a built environment that supports residents’ quality of life. By doing so, this case study illustrates the limitations of municipal planning and planners in local government, pointing to more structural and strategic issues of metropolitan governance.


Introduction
The housing crisis in London is characterised by a lack of enough affordable housing which forces Londoners to live in expensive, overcrowded, and poor-quality conditions (Greater London Authority [GLA], 2018). This crisis is primarily caused by a continuous undersupply of housing (Gallent, 2016;Schmickler & Park, 2014), the commodification and financialisation of housing (Wijburg, 2021), as well as a lack of rent control policy in the city. According to a recent BBC News (2019) report, this has only been made more acute during the Covid-19 pandemic. To solve this crisis, the current Mayor of London has established the London Housing Strategy (GLA, 2018). Although the strategy recognises the importance of key policies such as private rental control, the diversification of the construction industry, and leasehold improvement and reform, the main emphasis is on increasing the supply and construction of new homes. In fact, this report estimates that 66,000 new homes need to be built every year for the next 20 years across the city. But where and in what form will this growth be accommodated?
The history of urbanisation in London until the 20th century is of predominantly low-rise development, with some examples of robust medium-height blocks delivered by the London County Council (Morris, 1994) during the early decades of the century. However, in the post-war era, high-rise initiatives of social housing started to emerge. These have generally been described as unsuccessful, and numerous developments of this type have recently been demolished and redeveloped (Baxter & Lees, 2009). This narrative suffered a shift in the early 2000s, when the first Mayor of London, Ken Livingstone, accessed the office and openly showed his support for this form of development (Charney, 2007). Although different institutions such as Historic England and the Commission for Architecture and the Built Environment opposed this approach, tall buildings started to emerge, primarily in the centre of London and almost entirely as offices (New London Architecture, 2018). Since the creation of the GLA in 2000, there have been three distinct stages with different approaches to the role of high-rise buildings in the city and its planning: the first under Ken Livingstone (Labour) between 2000 and 2008, a second phase under Boris Johnson (Conservative) between 2008 and 2016, and the current one under Sadiq Kahn (Labour) since 2016. The period under Livingstone's mandate has been widely studied (Appert & Montes, 2015;Glauser, 2019), uncovering his key motivations to use skyscrapers and starchitects to situate London as a global metropolis that could attract investment, as well as the key governance mechanisms through which multiple actors were brought together to shift the discourse around the need to transform and modernise the city's skyline (White & Serin, 2021, p. 27). This article explores the next two stages between 2008 and 2020, as these remain understudied.
As a general overview, under Boris Johnson and Sadiq Kahn, the construction of high-rise buildings continued and accelerated (New London Architecture, 2021). As a result, one of the key post-2008 characteristics is the proliferation of numerous high-rise clusters of buildings, as opposed to single flag-ship high-rise developments. This is the irruption of new urban environments where tall buildings represent the dominant type, and where the relationship of buildings and the public realm introduces a new set of challenges regarding their appropriate scale, intensity of use, and questions of ownership and sustainable management. Another important characteristic of these later stages is the expansion of this form of development to hosting diverse uses, including housing and mixed-use buildings. I will refer to these new forms of residential neighbourhoods as vertical neighbourhoods. The proliferation of this form of growth meant that a much broader set of architects, builders, and developers would join the construction activity of these buildings. In consequence, as discussed by English Heritage and Commission for Architecture and the Built Environment's (2007) report, the quality of buildings and the public realm have been compromised, with important quantitative and qualitative deficits. How policy and actors are trying to address these deficits in highrise and high-density neighbourhoods by proactively shaping these new environments is this article's object of enquiry.
In this article, I draw on the findings of mixed-method research investigating the production, regulation, and shaping of high-density and high-rise neighbourhoods in London. The aim is to provide an insight into the tools through which different government tiers-local planning authorities (LPAs thereafter) in particular-in the discretionary and market-led UK planning system can shape vertical neighbourhoods in its broader sense, moving beyond the problematique of single high-rise buildings. While recent publications have produced a comprehensive review of some of these tools (Short, 2012;White & Serin, 2021), including management frameworks and design guidelines, these instruments are generally presented as non-problematic and/or subject to opposition, resistance and/or transformation. In this article, I reflect on the processes of production of these policy tools, as well as comparatively analyse their current and potential efficiency to proactively shape these emerging residential environments through the planning process.
In order to do so, I bring two fields of literature into a single interpretative framework. The first is on tall buildings and explains the construction of these residential landscapes as a result of macro-level and structural economic forces, as well as a result of the use of different design and planning tools to shape their form. This body of literature has two important gaps. First, it has merely focused on the place-shaping and planning analysis of wider strategic heritage impacts of single high-rise buildings, as opposed to reflecting the multiple challenges and deficits of high-rise building clusters. Second, this body of literature has focused on the structural economic pressures driving this form of development and has been less concerned with the analysis of the specific decision-making processes in a multi-level government setting. I, therefore, adopt a multi-scalar and multi-level governance framework to understand how new high-rise neighbourhoods are being constructed and contested through the different tiers of government, and ultimately to better understand why such important quality deficits exist in these new residential landscapes. In short, in this article, I investigate the ability of LPAs and local planning tools to shape different aspects of this growth.

A Multi-Scalar and Multi-Level Governance Critical Exploration of Density and Height
The planning of tall buildings and high-density developments in Europe has recently entered the academic agenda more vitally, as cities that historically restricted and refused high-rise buildings have lately embarked on permitting a significant number of developments of this type (Drozdz et al., 2017;Pipe, 2018). This scholarship exploring high density and height can be divided into two distinct bodies. On the one hand, a critical enquiry into the underlying and structural factors driving this form of development and growth, such as globalisation (Atkinson, 2019;Graham, 2015) and urban neoliberalism (Nethercote, 2018;Rosen & Walks, 2013), and, on the other hand, an emerging body of work, investigating from a place-shaping perspective some of the key challenges associated with the design of high-rise buildings (Al-Kodmany, 2017). On the former, authors have pointed to some of the main macro-level conditions shaping this form of growth such as market-orientated planning policymaking, profit-driven development, and the privatisation and financialisation of housing provision (Flynn, 2016;Robinson & Attuyer, 2020). On the latter, we can find urban design studies that investigate questions regarding the place-shaping of tall buildings, particularly their impact on the heritage of cities (Short, 2012), technical aspects to achieve more environmentally sustainable buildings (Al-Kodmany, 2018;Szolomicki & Golasz-Szolomicka, 2019), as well as the various impacts these developments have on residents' quality of life and the life of cities more generally (Blanc & White, 2020;Du et al., 2017;Fisher & McPhail, 2014).
While the analysis of the structural forces resulting in the vertical development of residential landscapes across the world has been widely studied mainly in terms of urban intensification (Charmes & Keil, 2015;Keil, 2020;Rosen, 2017), the analysis of how these have materialised in the built environment in different physical forms and spatial configurations across different contexts is more limited. As pointed out by White and Serin (2021), how urban intensification forces translate into specific policies is a context-dependent issue influenced by the regulatory planning system and the political context within which regulatory bodies develop those regulations. Recent reviews have brought to the fore a synthesis of tools and policy approaches across key cities in Europe and North America (Short, 2012;White & Serin, 2021), such as characterisation studies, environmental impact assessments, transferable development rights, or computational tools (GIS, VuCity, etc.), with two important shortcomings. First, literature has generally uncritically provided a synthesis of policies and tools to shape vertical neighbourhoods with a lack of analysis of their efficiency in meeting a set of outcomes. Second, this literature has narrowly focused on issues linked to strategic heritage protection (Cohen, 1999;Tavernor, 2007) and townscape conservation (Phelps et al., 2002), overlooking how other aspects of high-rise design are planned (or not), such as the quality of internal units (Allouf et al., 2020) or the relationship of high-rise buildings with the public realm (Al-Kodmany, 2017). This article provides an analytical framework to investigate the efficiency of different planning tools in meeting certain outcomes, at different scales of high-rise vertical neighbourhoods, and in a particular political and planning context. Furthermore, in the work above, one can recognise the macro-level structures driving urban growth and regeneration, as well as the more micro-level aspects shaping vertical neighbourhoods. This synthesis highlights a relatively overlooked space in-between, capable of explaining how and by whom current tools are being developed and operationalised, and how these macro-level settings condition, limit, or enhance their effective use for shaping good vertical neighbourhoods. This is particularly important as scholarship has tended to reduce the analysis of vertical neighbourhoods' production to a technical matter of height management or façade design. In fact, this tendency for the analysis of height production to focus on technocratic issues has meant that critical questions regarding the contextual political struggles taking place in shaping different aspects of vertical neighbourhoods have been downplayed, particularly concerning the multiple government tiers involved in producing policies and determining planning outcomes. To address this, we need to, while reflecting on the scope and capacity of local planning and planners in shaping those places, locate these within the broader decision-making process and governance framework. This means moving beyond the macro and micro levels to develop a situated and more nuanced explanation of why vertical neighbourhoods materialise the way they do, and the possibilities and challenges to improve this.

Uncovering the Production of High-Rise Neighbourhoods in Tower Hamlets
To investigate the production of high-rise neighbourhoods through a situated, multi-scalar, and multi-level governance approach, London emerges as a fascinating case study. As reflected by Gordon and Travers (2010), the metropolitan scale in which LPAs operate in London is paradigmatically complex. However, scholarship has either ignored or misrepresented the different roles, relationships, and frequent tensions between the local and metropolitan levels. These government tiers have been, generally, either assimilated (Appert, 2012) or their changing relationships-as well as attitudes to height-poorly investigated. This is particularly relevant in the context of the UK planning system, given its discretionary nature, which creates a space for negotiation for vertical developments. This article seeks to contribute to this literature by investigating the production of high-rise buildings and vertical neighbourhoods in Tower Hamlets (TH thereafter), to better understand how some decision-making processes within multi-level governance have influenced their final shape, with a particular focus on some of the key differences between Boris Johnson and Sadiq Khans' mandates.

Tower Hamlets at the Forefront of the Challenge
TH is London's densest borough, as well as the municipality with the highest number of tall buildings (New London Architecture, 2021). Despite this, TH is also the borough with the second-highest housing target, only behind Newham. This means 3,100 homes need to be built in the borough every year until 2025. Several factors can explain to a certain extent some of this data. First, TH is an inner London borough which covers much of the traditional "East End" (Figure 1). During the 18th and 19th centuries, this area experienced massive demographic growth as low-paid workers and immigrants moved there to work in the industries and docks, resulting in extreme overcrowding, the concentration of poverty, and high levels of disease and criminality. The area was heavily bombarded in the Second World War, given its industrial character, the presence of the docks along the Thames, and the important railway lines that connected London with the east. Numerous sites that were bombarded were redeveloped to house displaced residents (Palmer, 2004). Another contributing factor to the current built form and path of development is the numerous brownfield sites that have been, are, or will be very densely redeveloped to meet the borough's extremely high housing target. Finally, the north of the Isle of Dogs was redeveloped in the 1980s by the Canary Wharf group as the second financial centre in London, which radically changed the skyline of the borough, with the presence of some of the tallest buildings in the city ( Figure 2).
Until the late 1990s, the only high-rise buildings in TH were commercial buildings in Canary Wharf-with some brutalist residential buildings scattered through the borough-and most residential buildings were constructed as medium-height and medium-density.
High-rise buildings heights: However, since the early 2000s, the form of development starts to be increasingly denser and taller. Figure 3 shows the height and density of planning application proposals submitted to the Council within the 2000-2016 period. Some of these exceed the maximum density thresholds set by the GLA in the 2016 London Plan by more than six times. In a cross-borough comparison (Figure 4), TH is at the forefront of the creation of vertical neighbourhoods, with other boroughs closely following this path. We can therefore state that vertical neighbourhoods are becoming the main form of development across London.
By being at the forefront of this form of growth ( Figure 5), TH has faced the challenges of how to plan and shape high-rise and high-density developments for a long time, providing a good case study to reflect on their experience. Table 1 synthesises the numerous policies adopted at both metropolitan and local levels since the 1990s. From a metropolitan level, we can distinguish two stages. The first stage included London Plans 2011, 2013, and 2016, all adopted by Boris Johnson's administration; and the second stage with the draft publication of the London Plan in 2017 which was finally adopted in 2021 by Sadiq Khan. In the first one, the approach focused on mitigating negative impacts regarding heritage and environmental considerations and positively contributing to legibility from a strategic and skyline perspective. The approach under Sadiq Khan changes significantly, as it not only tightens the definition of what a tall building is but also requires LPAs to define areas where tall buildings are appropriate and introduce considerations of functionality at the building scale. In response to this metropolitan policy context, TH has adopted three development frameworks or local plans. While the 2010 Core Strategy and 2013 Managing Development Document capture the London Plan's strategic approach to the management of height-also including references to the provision of communal and open spaces at the intermediate scale-the 2020 Local Plan makes a radical move to more proactively manage high-rise buildings by setting tall building zones as well as developing a Tall Building Evidence Study (Tower Hamlets Council, 2018) which sets the path to the management of tall buildings in a more holistic and proactive way. Under these two local plans, a series of supplementary planning documents (SPDs) was adopted that try to shape high-rise buildings further. SPDs are non-statutory planning documents aiming to provide additional information to assist with the interpretation and implementation of policies set out within the local plan. While the SPDs adopted until 2016 take a place-based approach, merely indicating strategic heights accepted in an area, SPDs developed after 2016 take a more innovative approach trying to shape other scales of vertical neighbourhoods such as the intermediate and building scale. I will discuss three of them: South Quay Masterplan (SQM) SPD, adopted in 2016 and currently superseded; the High Density Living (HDL) SPD, adopted in 2021; and the Tall Buildings SPD, currently in the process of adoption. This article seeks to analyse the perception of planners on the effectiveness of these tools to shape vertical neighbourhoods.

A Mixed-Method Approach
To address the above question, this article uses a comparative and mixed-method approach: a qualitative analysis of interviews with urban planners given their active role in the planning process (Lawton, 2013), as well as a quantitative analysis of applications' decisions. The latter seeks to corroborate some of the claims made by urban planners and establish the scale and impact certain decision-making mechanisms have had on the development of vertical neighbourhoods. The first analytical part draws upon 12 open-ended interviews carried out in November 2021 with urban planners working at different stages of the planning process: from the initial stages of plan making-including the preparation of evidence and the development of policies-to later stages-including the implementation of policies through the negotiation of applications as well as case determinations and appeal processes. Furthermore, the framework of participants includes interviewees working at the municipal and metropolitan levels, as well as in the public and private sectors (as applicants or consultants for the public sector). The interviews aimed to assess to what extent urban planners think municipal planning in TH is suited and able to shape good quality vertical neighbourhoods from a social, environmental, and place-shaping perspective. The main questions discussed in the interviews were: 1. To what extent do you think you have enough policies and tools to shape vertical buildings and/or neighbourhoods? 2. If not, what is missing? 3. Are there any other factors that compromise your ability to shape this form of growth?
The second part of the analysis explores strategic planning application resolutions between 2008 and 2020. I gathered this data through secondary data sources, publicly available on the GLA's website as well as by TH's strategic planning reports. This analysis looks at what have been the predominant paths to determination and their results.

Discussion
The majority of planners in TH LPA believe the policy setting in the Council is comprehensive and layered in a way that, through negotiations with applicants, vertical developments can be shaped to achieve positive outcomes from a social, environmental, and place-shaping perspective. As per the multi-scalar analytical framework set out before, planners in the LPA reflected on the three key scales through which vertical neighbourhoods can be shaped ( Figure 6). These are (a) strategic, identifying areas where tall buildings can be built as well as the skyline or the three-dimensional relationship of their silhouette (e.g., stepping down principle); (b) intermediate, setting the urban structure of streets, open spaces, and infrastructures in which tall buildings sit; and (c) individual, defining the design characteristics and parameters of individual buildings. According to planners in TH, this stratification of different scales of policy is important as it provides more nuanced granularity to the different spaces to which the design of this form of growth should be attentive, as well as provides a structure to guide planning discussions with applicants. As a TH planner reflects on their experience in shaping highrise neighbourhoods: The planning of vertical cities requires understanding the form individual buildings take, as well as the relationships between them. I mean it is not only about each building but the whole: streets, open spaces, etc. In the borough, we are trying to shape all of them but there are certain aspects that have proven to be more In fact, as the quote and the overall analysis of interviews indicate, the initial broader affirmation of TH having the appropriate tools to shape vertical neighbourhoods is more nuanced. A discussion is provided next (Section 4.1) on the efficiency of regulations and policies to shape these three scales, and (Section 4.2) on the influence of the decision-making processes.

Strategic Scale: An Evolving Tool
All interviewees pointed to how the hierarchical nature of planning policies in the UK system determines the scope LPAs have in shaping vertical developments and neighbourhoods. The higher-tier the policy, the more weight it has in the determination of cases. An analysis of national and metropolitan policy documents shows that until the adoption of the New London Plan in 2021, policies primarily focused on the strategic scale. The policy framework did so through protected views (the earliest being the Richmond Hill, passed as an Act of Parliament in 1902), the London Views Management Framework (LVMF) Supplementary Planning Guidance (GLA, 2021), and through a series of high-level policies in subsequent London plans-the last one with this spirit being the "location and design of tall and large buildings" (GLA, 2016, p. 291). While protected vistas was a historical and somehow limited tool, the LVMF was produced to provide more certainty to developers on appropriate heights as well as to give more independence to the metropolitan government from the Secretary of State, to ultimately reduce the number of public enquiries (Appert & Montes, 2015;Charney, 2007;McNeill, 2002;Tavernor & Gassner, 2010). However, according to interviews, protected views as a place-shaping tool are very much limited to mitigating negative impacts on heritage aspects as opposed to defining heights strategically and proactively in an area. Although the 2016 London Plan provided further guidance-linking tall buildings to areas with high levels of growth and transport accessibilityinterviewees found these still limited in giving them the scope to shape where tall buildings should go: Those tools [views management frameworks] were ok when there were not as many tall buildings. When assessing one by one made sense, but when looking at a group of tall buildings in an area it is not enough. It is only about long-distance perception, and we were lacking more comprehensive planning of height. The case of Cubbit Property Holding Ltd in 2018 [Appeal Ref. APP/E5900/W/17/3190531, Inquiry 10/10/18] shows how weak the LVMF is for us. While we refused the application because it was too tall, the Secretary thought it was appropriate and positive for the skyline….With the adoption of the Tall Building SPD, we will regain control over the negotiation of heights and strategic decisions. (Interview 8) As the interviewee indicates, policies in place until very recently were subjective and not suited to the emergence of high-rise building clusters, hence calling for a more place-based and local approach to height. Indeed, the new London Plan (2021) provides two key additions that are changing policy weighting and increasing the power of LPA on the strategic scale. The first is the recognition of the importance of local views and the requirement for LPA to include these in local plans. The second is the delimitation of tall building areas where only tall buildings are permitted and where a more prescriptive and detailed definition of maximum heights within these areas is incorporated. This is a significant change since the first London Plan, which prohibited the imposition of "unsubstantiated borough-wide height restrictions" (GLA, 2004, Policy 4B.8). A bit before this new metropolitan policy approach, TH adopted an innovative policy in its 2031 Local Plan, identifying tall building zones, and further stating the need to prepare a Tall Buildings SPD to establish the potential for tall buildings and guide their height within the five tall building zones.

Building Scale: An Aestheticised Matter
On the contrary to the strategic scale, the planning and design of tall buildings at the intermediate and singlebuilding scales have for a long time received very limited attention at the national and metropolitan levels. Although London plans, since the first 2004 version, have referred to the importance of good and exceptional design in the case of large and tall buildings-Policy 4B.10 (GLA, 2004)-this has been kept as a rather "vague, subjective, and aestheticised matter" (Interview 2). To address these gaps, and more generally the deficient and poor quality of the built environment in London and across Britain (Commission for Architecture and the Built Environment, 2004), both national and metropolitan government tiers have launched two programmes with rather symbolic slogans: "Building beautiful" (Building Better, Building Beautiful Commission, 2020) and "good growth by design" (GLA, 2021). Despite this renewed attention to design, most interviewees at TH report their limitations regarding the particular urban form of high-rise developments: Design has entered the GLA's agenda, and also the national planning agenda. This is very welcome but look at the guidance documents they have produced. If you look at the Building Beautiful document, it is all low-scale and medium-scale examples. They do not acknowledge certain areas of the country are facing a very different problem. How do you apply those design principles in an area like the Isle of Dogs, or any other opportunity area? From a national level, they are clearly ignoring this form of city. (Interview 11) Although, as argued by the LPA's officer, the national report lacks any reference to that form of growth, the new London Plan introduces two policies with a more targeted and functional approach to high-rise buildings beyond aesthetic considerations (however limited to the scale of the building). This policy points to some of the main challenges tall buildings pose such as maintenance, management, servicing, and general access to high-rise buildings. However, as reported by TH planners, the policy is quite vague and lacks not only detail but also a clear definition of what good design means in the context of high-rise development. As a response to this deficit in national and metropolitan policy, the TH policy team developed the HDL SPD to provide further guidance on the good design of individual high-rise buildings. This SPD was developed in-house (Cerrada Morato & Mumford, 2021), focuses on the small scale, the building, and expands the definition of "good design to a solution that supports residents' quality of life" (TH Council, 2020). This new policy document has, according to the LPA's officers, been instrumental to shape and improve the quality of high-rise buildings: To address the gaps, or do not call them gaps, but further characterise and define what good design is in this form of development, the Council produced the HDL SPD. It is an innovative piece of work, supported by strong evidence and which points to key issues at the home level, communal spaces, circulation, etc. It is very context-specific and incredibly useful in not only determining cases but also in appeals. At the Bellerive House [APP/E5900/W/21/3283117] we used it a lot and the inspector agreed with us….It [HDL SPD] has received awards and everywhere we go, at every council we present it to, they say how important it would be to adopt it at a metropolitan level. But although the GLA planning team knows about it, they have not engaged in meaningful conversations. (Interview 2) As argued by the interviewee, this SPD targeting the building scale is working for TH officers, not only in the determination of cases but also when decisions are challenged on design grounds. This attention to design at the local level is, according to Carmona and Giordano (2022), further supported at the national level. However, as per the quote above, the HDL SPD case also shows that local policy production does not have much influence on a metropolitan policy level, suggesting local planners in a hierarchical planning system are in a disempowered position to influence policy and ultimately the form these developments take.
On a more general level, the analysis of interviews on the efficiency of the HDL SPD, and SPDs in general as tools to shape high-rise neighbourhoods, emphasise their lack of policy status, with two key implications. First, these are only considered a material consideration in the determination of cases. This is, they provide further guidance on local plan policies, but they cannot add additional requirements and need to be carefully worded as recommendations and not requirements. Furthermore, applicants do not need to meet all guidance, only show how these have been considered. As a result, although innovative in their approach, SPDs are per se a weak tool. Second, SPDs are very much limited in their scope if not strongly hooked to upper-tier policy. Therefore, if national or metropolitan planning policy does not introduce a requirement or policy hook, the LPA cannot introduce new policy requirements. Indeed, while the strategic and building scale seems to be well covered by current policy, the intermediate scale seems to be significantly compromised by a lack of hook to national and metropolitan policies. We will review this next.

Intermediate Scale: Within the "Red Line''
Analysis of interviews indicates that local planners find the shaping of the intermediate scale as the most challenging aspect, particularly the delivery of open spaces that meet the scale of development, and the provision of social infrastructures that allow these neighbourhoods to keep up with residents' demand. An analysis of metropolitan policy (GLA, 2021) shows there are very few quantitative requirements and qualitative guidance to shape this intermediate scale beyond aspects of environmental impact. In this context, the TH policy team produced a master plan to guide and shape the growth of one of the largest vertical neighbourhoods in the borough and London, the South Quay neighbourhood in the Isle of Dogs ( Figure 5). However, a visual analysis of what is being built on the ground suggests this policy document has not met its purpose and has been quite weak in ordering growth. Some interviewees have pointed to an underlying and structural issue in the area, the fragmentation of land ownership: The SQM tried to comprehensively plan for an area where tall buildings were emerging by establishing a street network, building form, etc. But developers were not willing or interested in that model. They wanted to maximise profit by developing to the maximum capacity within their red line. (Interview 7) As the quote indicates, one of the reasons the SQM SPD perimeter blocks approach (Figure 6) had very little impact is the resistance from developers to assemble land to comprehensively redevelop the area. According to most interviewees, developers' resistance could not be overcome, given the nature of non-prescriptive planning in the UK as well as the Council's lack of economic capacity to execute compulsory purchase orders. However, some planners at the local and metropolitan levels suggested that despite the structural limitations of the planning system, the LPA could have engaged earlier and more robustly with developers, as well as developed this policy framework earlier and well in advance of the strong growth that took place there.
Finally, an important aspect precluding the successful shaping of the intermediate scale according to TH planners is the non-prescriptive and negotiation-based UK planning system. As the interviewee below explains, the SQM is more European in its approach as it sets an urban structure-with a street network and strategic open spaces-the building alignments, their maximum heights, as well as suggesting occupation rates. However, the UK planning system operates under a different model of negotiations, articulated through "balanced decisions"-in which a planning officer balances pros and cons as opposed to an application having to meet all policies-and through developers' contributions to address any harm the development might pose. An urban planner discusses the limitation this system poses to deliver good quality vertical neighbourhoods at the intermediate scale: This negotiation system is proving not to be fit for purpose in shaping areas where tall buildings are emerging. The scale of these developments requires larger open spaces. But the way we operate is each developer must provide open space within the red line. The result? We have a series of piecemeal and fragmented open spaces, but these are small. They do not respond to the scale of these neighbourhoods. We need to strategically create open spaces that are meaningful. (Interview 3) As the urban planner points out, the scale of open spaces secured through planning in the Isle of Dogs is very deficient, as it does not match the scale (in terms of density and height) of the neighbourhood (see Figure 7). However, as the TH plan-making team prepares for the new iteration of the local plan, an important observation is made which sends a positive message for the future of intermediate-scale planning: Site allocations are now expected to be more like masterplans, setting open space requirements, housing targets, etc. It is much more prescriptive, but to do so we will need to be looking in detail at things such as economic viability, and environmental issues. It will require much more work at an early stage. I think the "battles" at the planning stage will be pushed earlier on in the process. Things will be agreed upon much earlier. (Interview 5) According to the quote, this new approach will result in stronger policy guiding vertical growth. In this new scenario, local planners anticipate difficulties in the adoption process. In fact, they suggest that a new paradigm might be emerging in which negotiations between LPAs and applicants might be shifting from the planning stage to the plan-making stage.

Decision-Making
Despite having the policies that would allow planners at the local level to shape vertical neighbourhoodsalthough, with certain limitations as discussed in the section above-all urban planners at the local level reflect on the two structural limitations of the decision-making process: housing targets and alternative routes to cases' determinations.

Housing Targets
All planners at local and metropolitan levels recognise the huge pressure LPAs have to meet housing targets, which in the case of TH is the second highest across London's boroughs. Despite the good quality of local policies in place, urban planners explain that this imposition from higher tier government means they do not control the intensity and path of growth. According to interviewees, this factor significantly influences their decisions as they feel under pressure to support proposals that deliver as many homes as possible, sometimes having to prioritise quantity over quality. This is further exacerbated as there is a political commitment to deliver as many affordable homes as possible. Therefore, decisions tend to favour any development that meets between 35 and 50% of affordable homes. This mechanism of hierarchical control from higher-tier governments has been recently explored (Raco et al., 2022). However, from a negotiation and place-shaping perspective, an officer notes: These [housing targets] should not be an excuse that justifies the poor quality of some of these new neighbourhoods. I think officers are negotiating the quality of these buildings, the façade, flats, etc. But what is not being acknowledged is, if you know you will have to deliver this form of city, why don't you embrace it and let buildings go higher but protect enough street widths and enough open space between them? I do not think the number of flats or height is the problem, it's the occupation rates. We should always go back to place-making principles. Height is only one of the many parameters in the matrix. (Interview 2) As articulated by the interviewee, despite the intensity of growth, planners can develop policies and negotiate applications shaping some key aspects of vertical neighbourhoods.

Appeals and Public Hearings
In addition to housing targets, interviewees have claimed that the main factor that has influenced the shape of TH's vertical neighbourhoods is two decision-making mechanisms for the determination of cases: appeals and pub-lic hearings. Indeed, appeals have been recognised in high-rise literature as an important governance mechanism in London. As reported by Appert (2012), this mechanism was used during Livingstone's mandate by the central government to control and stop the proliferation of tall buildings, hence as a form of national control over metropolitan powers. According to interviewees, this mechanism continues to play an important role in the form and shape of vertical neighbourhoods, this time also intervening at the local level: Appeals to the Secretary of State have been very influential in how the landscape of buildings has evolved. And these have set the precedent for future high-rise growth. A good example is Whitechapel Estate [ Figure 8]. That is not within a tall building zone but they [Secretary of State] accepted it. And with some of those precedents, you know….We are always on the back foot, always behind….We know that if the case goes to appeal, the cost for the borough would be phenomenal. It does not mean that of course, we recommend something different as to what we consider a balanced and fair assessment, but it cannot be denied that it [previous appeals] is kept in the back of our minds as well as I am sure of the Committee. (Interview 3) A report produced by the TH Strategic Planning Team (TH Council, 2019) corroborates to a certain extent the claim above. Data shows that between 2015 and 2019, 264 total major planning decisions were appealed to the Secretary of State. However, only three major decisions were overturned at appeal. This indicates that although this mechanism has not been significant in terms of cases overturning, its sheer volume has created unprecedented strain in a significantly under-resourced LPA. In fact, as pointed out by the interviewee and confirmed by  Dunton (2016). the report, the economic and human consequencespreparation of the process, officers' time, and consultants' cost to support the LPA through the process-are a tremendous burden. According to this report, an appeal of a major planning application can cost around £100,000.
Furthermore, a more recent mechanism of metropolitan determination commonly known as "call-ins,'' "public hearings," and/or "representation hearings" has been completely overlooked in academic research. This alternative route to the LPA's direct determination was introduced in 2008 as part of the Mayor London Order. Under this directive, the GLA can call in cases if considered of strategic importance-generally in terms of the number of units and height-before these are determined by the LPA. This alternative mechanism to obtain planning consent has been pointed out by interviewees as having had a great impact on the shape of vertical neighbourhoods in the borough: setting approved cases in a system that is primarily driven by precedents. First, interviewees claim that, since 2008, the GLA has called in numerous cases in the borough to give them permission in opposition to the criteria of the LPA and set the precedent of a tall building in an area. This means that cases brought forward later can claim the existence of a tall building in their proximity and replicate (if not increase) the height of their proposal. Columbus Tower, a 63-storey development, in the Isle of Dogs (Figure 9) is the first scheme the GLA called in, and, as the intervie-wee below explains, one of the first buildings in the Isle of Dogs clearly ignoring the stepping down principle: If you look at the cases that Boris called in when he was the mayor, you can see that the tallest buildings were consented to by him. Columbus Tower is an atrocious example of the mechanism he established. Nothing in that area justified that scale of height. He has had a key responsibility in how the borough has transformed. Once you have a few schemes of that height the pressure is enormous. Even if some of them were never built, the pressure on the Strategic Committee and the Council is enormous, there is the threat that the case can be called in and then the Council loses the ability to negotiate further contributions. (Interview 7) An analysis of GLA call-ins in Table 2 shows that 30% of cases during Boris Johnson's administration were in TH. As argued by the interviewee, this mechanism not only sets a precedent that compromises more strategic planning of heights in an area or the overall quality of the architecture but more fundamentally it also jeopardises a key contribution method for the planning of the intermediate scale. This is because the GLA becomes the negotiator for section 106 contributions. However, on this point, there is disagreement among officers as some report being consulted and involved in section 106  negotiations despite TH not being the planning authority determining the case.
Although this mechanism has not been used by the current GLA's administration in TH as much as the previous one (only one case), this is still significant across other LPAs. Indeed, an interviewee pointed to the dual role the GLA plays in how these vertical neighbourhoods are shaped: The GLA has two "hats." You have the policy team that understands and supports us through quality-led and design-led proposals…but then you have the GLA "planning hat." And they are very uncritical, always pushing for more height and density. They are in many instances closer to the developer than to us. And that weakens our position. (Interview 6) The GLA's conflicting role mentioned in the quote above has become more acute under Sadiq Khan, as the New London Plan's optimisation-with a quantity emphasisand design-led approach-with a quality priority-are perceived by local planners as irreconcilable.

Too Much or Too Little Metropolitan Interfering?
Despite the consensus on how the hierarchical planning system and decision-making processes constrain the capacity of municipal planning and urban planners at the local level to design quality vertical neighbourhoods, two of the interviewed planners offered a dissenting view. The interviewee below suggests the problem of the proliferation of tall buildings of poor quality across London could be the result of not too much interference from the GLA but a rather weak metropolitan policy: A frustration I always had is the GLA pushes boroughs to do things, and each comes with its own interpretation. But as a city, you need a city-wide approach. It is a bit top-down, but there should be a principle of where tall buildings should be in London, not just permit some boroughs to allow new clusters of tall buildings in what seems quite arbitrary locations. It is alright to have tall buildings in the centre or the Canary Wharf, but when you have tall buildings in other random places then it impacts the overall sky-line. And we don't want to see height in every town centre or in marginal areas. There, the quality of developments is not going to be as high, as good. You really want to avoid that. (Interview 12) This opens the question as to whether the solution to achieve quality high-rise environments across London lies in the provision of more prescriptive policy at a metropolitan level. As the interviewee argues, this approach will not only be more robust in terms of design standards but also more comprehensive across boroughs.

Conclusions
Vertical urbanisation has primarily been explored and explained as a phenomenon driven by macro-level economic and political factors, such as the flows of capital (Nethercote, 2018) and urban neoliberalism (Rosen & Walks, 2013). The impacts of the emergence of these new urban landscapes have also been explored, but this has generally been assessed from a strategic perspective, primarily focused on heritage conservation and skyline management. Overall, the design and planning of vertical neighbourhoods have been described as a technical and rational matter, and fundamentally decided at the local level. In this article, I have argued that to understand the process of vertical urbanisation and to examine how these have been constructed and contested, a situated, multi-scalar, and multi-level governance exploration is necessary.
The multi-scalar analysis of vertical neighbourhoods in TH has shown that the policy framework targets three different scales: strategic, intermediate, and building. While TH planners working at different stages of planning think the strategic and building scales can be shaped by LPAs through the Local Plan and subsequent SPDs, the shaping of the intermediate scale is compromised by the discretionary and market-led planning system in the UK. Additionally, although the historical production of municipal planning policy regulating high-rise buildings and vertical neighbourhoods has been strongly conditioned and generally weakened by higher tier policies; recent changes at metropolitan and national levels indicate a more pro-active role is expected from LPAs to guide this form of growth. One of the key outcomes that are expected is the shift of negotiation to the early stages of the planning development, which will provide the opportunity for a more comprehensive and project-led plan-making at the strategic, intermediate, and building scales.
Multi-level governance analysis has revealed that despite the robust policy framework that TH has had from as early as 2013, TH urban planners' ability to shape vertical neighbourhoods is compromised by decisionmaking governance structures and alternative routes for case determination. According to local urban planners, these have had a significant influence on the shape of vertical neighbourhoods, suggesting local democratic accountability has been compromised by the metropolitan government and proposing that LPAs' scope is reduced in a multi-tier governance framework. This is an important contribution to literature as the relationship between metropolitan and local government tiers is more complex and prone to tensions than has been depicted. The article concludes by suggesting that a solution to better shape vertical neighbourhoods may lay in a combination of upscaled planning of the strategic scale while enhancing the role of LPA in planning the intermediate and building scale.